Sometimes the interpretations of works are over the top. That's true.

But in most cases there are a lot of "empty spaces" in books where the reader jumps in and forms his own interpretations - mainly based on life experiences. Take a book like Salinger's "The Catcher in the Rye" and you get very different interpretations. People who faced similar experiences like the protagonist Caulfield will see a deeper meaning in the plot line than someone else who just says "Okay, what's the big deal here?".